When electrical equipment is arranged for alternate connection between two sources of power such as with a standard power system and with an auxiliary or emergency power system, an interlock arrangement is employed to prevent both power sources from being simultaneously connected to the equipment.
The following U.S. Pat. Nos., namely, 3,319,020; 3,312,797; 3,647,997; and 3,705,280, are representative of interlock arrangements for various rated circuit breakers and electric switches.
U.S. Pat. No. 3,778,633 entitled "Automatic Electric Power Source Transfer Apparatus" describes a "walkingbeam" interlocking mechanism consisting of a bell crank lever arrangement with a pivotally mounted post at each end of the bell crank. The post extends through openings in the bottom of the circuit breaker case to interact with the circuit breaker movable contact arm.
U.S. Pat. No. 4,499,344 entitled "Interlock Arrangement for Circuit Breaker Compartments" describes a complex mechanical interconnection between large ampere-rated circuit breakers mounted within separate compartments.
One purpose of the instant invention is to describe a simple and inexpensive interlock arrangement for molded case circuit breakers of the type utilizing a molded plastic crossbar assembly.